package part14;

/**
 * @author wcj
 * @Date 2021/5/26 17:08
 * @Version 1.0
 */
public class Part1414 {

}

class Person {
    private final String first;
    private final String last;
    private final String address;

    public Person(String first, String last, String address) {
        this.first = first;
        this.last = last;
        this.address = address;
    }

    @Override
    public String toString() {
        return "Person:" + first + " " + last + " " + address;
    }

    /**
     * 空对象，暂时没有摸索到它的实际用途
     */
    public static class NullPerson extends Person implements NULL {
        private NullPerson() {
            super("None", "None", "None");
        }

        @Override
        public String toString() {
            return "NullPerson";
        }
    }

    public static final Person NULL = new NullPerson();
}

interface NULL {
}
